source: azure_iot_hub/trunk/musl-1.1.18/src/string/wcsspn.c@ 388

#include <wchar.h>

size_t wcsspn(const wchar_t *s, const wchar_t *c)
{
        const wchar_t *a;
        for (a=s; *s && wcschr(c, *s); s++);
        return s-a;
}